The overall objective of this project is to determine the factors which regulate the uptake and metabolism of fatty acids in the liver and which thereby influence the availability of fatty acids for plasma lipoprotein formation. Mechanisms which control the partition of free fatty acid utilization between the pathways of oxidation and esterification in rat liver will be investigated in a newly-developed cell-free system of mitochondria and cytosol, in isolated liver cells and liver cells in culture. Emphasis will be placed on the molecular interactions by which direct rate-control of fatty acid oxidation is exercised (which thereby determines the rate of esterification). These studies will explore the action of antiketogenic agents (fructose, glycerol and dihydroxyacetone) and the influence of the phosphorylation state ratio, adenine nucleotide transport, pyridine nucleotide and flavin redox states, carnitine acyltransferase activity, acylation states of CoA, and anion translocases. The hormonal involvement of insulin will be investigated in the primary liver cell culture. Our recent observation that calcium regulates the mitochondrial NAD oxidation-reduction state of liver cells oxidizing fatty acids will be extended to define the nature of the intracellular interaction between fatty acids, calcium and the pyridine nucleotide redox state. Effects of calcium on NADH production and utilization rates and interactions with the respiratory chain are projected for analysis. Plasma lipoprotein production by liver cells will be investigated with emphasis on the basic factors which stimulate and retard component syntheses, assembly and secretion. Effects of carbohydrate and insulin on lipoprotein production will be measured. Liver cells will also be provided with an elevated supply of lipid precursors for examination of the sequence of responses leading to elevated lipoprotein formation. The studies outlined herein are organized to provide definition of the mechanisms which govern the rates of the above intrahepatic processes related to lipoprotein formation and which thereby influence the plasma lipid concentration.